Topanga Canyon State Park, Santa Monica
Topanga Canyon State Park is a fairly large park, considering its location within a city. It has an extensive network of trails leading through and above Topanga Canyon.
The landscape of this park is specifically interesting in that it contains acres of open grassland in addition to live oak and a variety of plant species. I didn't get to hike any of the more extensive trails in this park as my visit there was so brief. But I was told it is the favorite of hikers and mountain bikers in the area.